Traditional rectifier circuits in which energy is first stored in a capacitor that is charged to a peak voltage from a rectifier bridge have low power factors. These circuits also usually generate markedly distorted sinusoidal currents that are liable to cause disturbances in a connected public switched network. Various solutions to this problem have been proposed.
U.S. Pat. No. 5,383,109 teaches a rectifier circuit that has a high power factor. The circuit is constructed as a full-wave rectifier bridge for high mains voltages and as a voltage doubler for low mains voltages. Output voltage control and power factor correction are achieved with the aid of a high frequency booster circuit that includes two coils which are parallel-coupled at low mains voltages and series-coupled at high mains voltages. The circuit also includes two series-coupled transistors which function as pulse wave modulators.
One drawback with the aforedescribed circuit is that it includes double transistors and double switches, causing the circuit to be unnecessarily complicated.